1. Field of the Invention
The invention relates to an enclosed electrical switching station, and it resides more specifically in a momentary-maintained mechanism actuated by a lever-operated switch.
2. Description of the Prior Art
Momentary-maintained electrical switches have been provided for special motor control applications as disclosed in the G. 0. Wilms U.S. Pat. No. 2,050,076, assigned to the same assignee as is the present invention. Wilms is illustrative of a momentary-maintained pushbutton station having a maintained contact in the form of a conducting ring encircling a fiber disc and carried by the lower stem of an axially moveable "stop" button. The conducting ring is normally engaged by two inwardly biased spring metal terminal members. The "start" button provides a conducting disc member arranged for momentary engagement with spaced apart terminal members. The stem of this button includes radially extending flanges engageable with opposite sides of one end of a pivoted lever member for moving the lever in opposed axial directions. The opposite end of the lever releaseably engages the fiber member of the "stop" button.
The Wilms patent taught a relatively simple arrangement, but required terminals or stationary contacts specifically designed for the particular application.
Later, there were provided pushbutton stations containing a selection of contact modules of varying contact configurations, assembled in accordance with the desires of an ultimate user. The operating mechanism of these comprised a button-type actuator of a particular configuration which would cooperate with any of the several modular contact blocks. This arrangement permitted an electrician to add individual contact blocks or modules in various combinations, all of which combinations could be operated from the same type of actuating mechanism. Obviously, this construction required that an over-center, toggle arrangement be built into the actuator mechanism, rather than in the individual contact assembly as was disclosed in the Wilms patent.
Lever-operated switch mechanisms were later introduced as taught in the DeSmidt U.S. Pat. No. 3,320,395 for use with certain type of enclosures. This construction used a contact block which was limited to a specific contact arrangement, and not of the momentary-maintained operation of the Wilms as is the present invention. Momentary-maintained, lever-actuated, contact arrangements utilizing modules, such as those of the Boysen U.S. Pat. No. 3,514,554, were not available until the conception of the present invention. Both the Boysen and DeSmidt patents were also assigned to the assignee of the present invention.